The lymphatic system is central to overall immune function and fluid balance. The osteopathic profession strongly espouses the value of applying manipulative procedures to the body to augment lymphatic flow to improve overall immunity and interstitial fluid homeostasis. Osteopathic manipulative treatments (OMT) are used today to treat edema and infection by augmenting lymph movement. This investigation will determine for the first time whether and to what extent OMT increases lymph flow and alters its chemical and immunological properties. This research will contribute to the overall goals of the proposed DCRC on the mechanisms of OMM by close association with a basic physiologic principle of health. Conditioned dogs will be surgically instrumented to measure flow in the thoracic lymph duct, intra-thoracic, intra-abdominal, and aortic pressures, and cardiac output. To test the hypotheses that OMT significantly enhances lymph flow and is potentially efficacious in the treatment of edema and infection, experiments will be conducted to: 1) Quantify the effects of three OMT procedures (thoracic, abdominal, and pedal lymphatic pumps) on lymph flow using single, repeated, and daily applications of OMT, 2) Compare OMT with treadmill exercise as interventions to increase lymph flow, 3) Evaluate the extent to which expansion of extracellular volume will enhance the action of OMT and treadmill exercise as interventions to increase lymph flow, 4) Determine the effects of OMT on intra-thoracic, intra-abdominal, and aortic blood pressures and on cardiac output and correlate changes in thoracic lymph flow with changes in these variables during OMT and treadmill exercise. To test hypotheses that increases in lymph flow produced by OMT are potentially efficacious for treatment of edema and infections, experiments will be conducted to: 1) Develop a model of abdominal edema and evaluate the impact of OMT on this condition, 2) Develop a technique to chronically sample thoracic duct lymph and determine the effects of OMT on lymph chemical composition and immunological properties. The results of this investigation are expected to establish a scientific foundation for widely used osteopathic manipulative treatments aimed to increase lymph flow. This project will also produce new knowledge on physiological functions of the lymphatic circulation.